1. Field of the Invention
The present invention relates generally to biomass gasification and more specifically it relates to a biomass gasification system for efficiently extracting heat energy from biomass material.
2. Description of the Related Art
Biomass gasification processes have been in use for years for converting biomass into an energy source. Biomass gasification applications include water boiling, steam generation, drying, motive power applications (e.g. using the producer gas as a fuel in internal combustion engines), and electricity generation.
Almost all kinds of biomass with moisture content of 5–30% can be gasified. Examples of suitable biomass include forest slash, urban wood waste, lumber waste, wood chips, sawdust, straw, firewood, agricultural residue, dung and the like. Under controlled conditions, characterized by low oxygen supply and high temperatures, most biomass materials can be converted into a gaseous fuel known as “producer gas”, which consists of combustible mixture of nitrogen, carbon monoxide, and hydrogen. This thermo-chemical conversion of solid biomass into gaseous fuel is called biomass gasification.
Biomass gasification has many of the advantages associated with using gaseous and liquid fuels such as clean combustion, compact burning equipment, high thermal efficiency and a good degree of control. In locations where biomass is already available at reasonable low prices (e.g. agricultural areas) or in industries using fuel wood, biomass gasifier systems offer definite economic advantages. Biomass gasification technology is also environment-friendly, because of the fuel savings and reduction in CO2 emissions.
The main problems with the application of biomass gasification systems have been economic, not technical. For example, conventional biomass gasification systems are typically suitable only for large-scale operations and not small-scale operations. Also, the product from gasification is mainly a heat source, and the low value of these products in today's market is insufficient to justify the capital and operating costs of conventional biomass gasification systems. Hence, there is a need for a biomass gasification system that is efficient and cost effective to operate with low cost biomass.
An example of a patented device this is related to the present invention is illustrated in U.S. Pat. No. 2,171,535 to Berg et al. for an incineration system for disposal of refuse having high moisture content. However, the Berg et al. patent reference does not have a piston feeder structure, a rotating grate within the primary combustion chamber, a silica collector system nor an oxygen mixer between the primary combustion chamber and the secondary combustion chamber.
While these devices may be suitable for the particular purpose to which they address, they are not as suitable for efficiently extracting heat energy from biomass material. Conventional biomass apparatus do not efficiently extract heat energy from the biomass material.
In these respects, the biomass gasification system according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of efficiently extracting heat energy from biomass material.